Light strip and method for making a light strip

ABSTRACT

A light strip has a flexible enclosure extruded around a pair of conductors. The enclosure contains a lighting assembly with one or more flexible substrates that are each populated with a plurality of light circuits. The substrates are spaced from the pair of conductors. The lighting assembly has a plurality of connecting devices for electrically coupling the lighting assembly to the pair of conductors.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/726,764, filed on Jun. 1, 2015, which claims the benefit of UnitedStates Provisional Patent Application, Ser. No. 62/006,382, filed Jun.2, 2014, the contents of both being hereby incorporated by referenceherein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to lighting strips and methods for makingthe same, and in particular to extrusions and extrusion methods for suchlight strips.

2. Description of Related Art

Flexible printed circuit boards have been manufactured in strips thatare populated with light emitting diodes. The strips can be mounted in atransparent tubular sleeve that is easily mounted in a variety oflocations. These lighting strips can be placed inside cabinets, alongcorridors to light a walkway, or any place where a compact lightingsource is required.

Light emitting diodes have relatively small forward voltage drops andtherefor require a voltage conversion unit such as a transformer, whichadds to the complexity of the installation. Also known light strips haveincluded ASICs to regulate the applied voltage, but these ASICs tend tobe large, generate much heat, and have a tendency to pull off theunderlying, flexible printed circuit board.

Known lighting strips have flexible circuit boards that carry both thelighting elements and buses that carry power throughout the strip. Whenthe strip is relatively long, the buses must carry significant currentthat tends to heat a flexible circuit board and degrades the performanceof the adjacent LEDs, possibly causing them to fail. Many applicationsrequire an especially long lighting strip. In such cases a number ofshorter strips are spliced together and mounted in a common sleeve, endto end. In this case the buses on each strip are serially connected andmust carry current for all the lighting elements in the several strips.Such a common bus carries even more current, and generates even moreheat that seriously affects the lighting elements.

Also, it can be difficult to mount in a single sleeve, long lightingstrips or a number of serially connected lighting strips.

See also U.S. Pat. Nos. 3,786,173; 4,032,210; 4,990,098; 5,032,960;5,296,648; 5,337,225; 5,559,681; 5,681,179; 5,833,358; 6,113,248;6,244,893; 6,673,292; 6,773,286; 7,249,980; 7,753,577; 8,052,303;8,262,250; 8,398,262; 8,635,769; 8,641,229; and 8,714,772.

SUMMARY OF THE INVENTION

In accordance with the illustrative embodiments demonstrating featuresand advantages of the present invention, there is provided light stripincluding a pair of conductors, and a flexible enclosure extruded aroundthe pair of conductors. The light strip also has a lighting assemblyincluding one or more flexible substrates positioned within theenclosure and populated with a plurality of light circuits. The one ormore substrates are spaced from the pair of conductors. The lightingassembly has a plurality of connecting devices for electrically couplingthe lighting assembly to the pair of conductors.

In accordance with another aspect of the invention, a method is providedfor making a light strip having a pair of conductors and one or moreflexible substrates populated with a plurality of light circuits. Themethod includes the step of extruding a plastic material around the pairof conductors to form a flexible enclosure sized to encompass the one ormore flexible substrates and maintain a spacing between the pair ofconductors and the one or more flexible substrates.

By employing apparatus and methods of the foregoing type an improvedlighting strip is achieved using techniques that ease manufacture andassembly. In a disclosed embodiment a transparent sleeve is extrudedaround a pair of conductors that supply power to the lighting strip. Theflexible printed circuit board carrying the LEDs is spaced from thesesupply conductors and are not overheated by them. In this embodiment aflexible circuit board has a number of separate strings of LEDs whosecurrent is limited either by a resistor or a depletion mode field effecttransistor. Each string of LEDs on the flexible circuit board has itsown dedicated pair of solder pads that are each connected to one end ofa jumper whose other end connects to one of the supply conductors.

These disclosed jumpers may be soldered in place in advance, so that theflexible circuit board and supply conductors are simultaneouslycoextruded into a flexible sleeve, with extrudate partially envelopingthe jumpers. The printed circuit board is not enveloped by the extrudateto avoid trapping it in an insulating layer that prevents heatdissipation.

In some cases the flexible sleeve can be extruded around just the supplyconductors and part of the jumpers, which jumpers to or connected to thesupply conductors but not to the missing flexible circuit board. In thatcase the sleeve will have a longitudinal slit (a split). The split incan be opened with an appropriate tool that allows an end of theflexible circuit board to be inserted into this sleeve. Thereafter thetool is slid back to open progressive positions in the longitudinalsplit, allowing the rest of the flexible strip to be placed inside thesleeve. Thereafter, an assembler can solder the free ends of the jumpersto the solder pads on the flexible circuit board.

In either case, a number of separate flexible printed circuit boards canbe installed end to end, but instead of being directly interconnected,they are simply connected to the supply conductors embedded in theflexible sleeve.

The disclosed LEDs have a relatively high forward voltage drop. Thisallows one to apply a higher voltage to a string of LEDs. In a disclosedembodiment the LEDs are arranged to handle the rectified line voltagefrom an ordinary utility line, without the need for a stepdowntransformer or other device for reducing the voltage applied to thelighting circuit. The rectifying circuit can be placed in a housing thatis in line with a cord having with a plug that connects to an ordinaryutility outlet. Alternatively, the rectifier circuit can be placed in ajunction box and hardwired to a power line. A separate cable can runfrom the junction box to the lighting strip.

In a disclosed embodiment, this rectified line voltage is applied to thelighting strip with a connector having a shell containing a pair ofpointed pins. When the connector is pushed onto a lighting strip thepointed pins are inserted into the coextruded supply conductors whichare made of stranded wires that are easily invaded by the pointed pins.The shell of the connector matches the asymmetrical periphery of theflexible sleeve containing the flexible printed circuit board. Theasymmetry is arranged such that the connector can only be placed on oneand of the flexible sleeve to avoid a reversed polarity.

BRIEF DESCRIPTION OF THE DRAWINGS

The above brief description as well as other objects, features andadvantages of the present invention will be more fully appreciated byreference to the following detailed description of illustrativeembodiments in accordance with the present invention when taken inconjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic diagram of a light circuit in accordance withprinciples of the present invention;

FIG. 2 is a schematic diagram of a rectifier circuit that may be used inconnection with the circuit of FIG. 1;

FIG. 3 is a schematic diagram of a light circuit that is an alternate tothat of FIG. 1;

FIG. 4 is a schematic diagram of the light circuit of FIG. 1 or 3replicated and segregated into separate groups that are each mounted ona flexible substrate to formal light strip;

FIG. 5 is a fragmentary, plan view of an upper copper lamination that ispart of the substrate associated with the circuit of FIG. 4;

FIG. 6 is a fragmentary, plan view of a lower copper lamination that ispart of the substrate associated with the circuit of FIG. 4;

FIG. 7 is a cross-sectional view of a flexible enclosure containing thesubstrate of FIGS. 4-6 to form a light strip;

FIG. 8 is a cross-sectional view of a the used to extrude thearrangement of FIG. 7;

FIG. 9 is a cross-sectional view of extrusion that is an alternate tothat of FIG. 7;

FIG. 10 is a perspective view of the extrusion of FIG. 9 being partiallyopened with tool that is being used to insert the substrate of FIGS.4-6;

FIG. 11 is a fragmentary, perspective view of a connector being used toconnect to the light strip of FIG. 7;

FIG. 12 is a perspective of the connector of FIG. of 11 connected to arectifier circuit;

FIG. 13 is an elevational view, partly in cross-section, showing to ahousing that contains a rectifier circuit that is an alternate to thatof FIG. 12; and

FIG. 14 is in end view of a clip used to hold the light strip of FIG. 7.

DETAILED DESCRIPTION

Referring to FIG. 1, the illustrated light circuit has six seriallyconnected LEDs, D1, D2, D3, D4, D5, and D6, in that order (hereinafterLEDs D1-D6). LEDs D1-D6 are connected cathode to anode and are allconnected to be forwardly biased by a positive potential at terminal V1.The anode of diode D1 is directly connected to terminal V1, while thecathode of diode D6 is directly connected to drain D of depletion modefield effect transistor Q1 (FET transistor Q1). In one embodimenttransistor Q1 was a model CPC3708 transistor supplied by IXYS,Integrated Circuits Division, although other types of transistors fromother suppliers may be used in other embodiments. Gate G of transistorQ1 is grounded, and its source S is connected through a parallel pair ofresistors R1 and R2 to ground. Accordingly, the power input to thislight circuit is applied across terminal V1 and ground.

Configured in this manner, transistor Q1 will conduct when relativelysmall voltage is applied across the transistor, but will shut off whenthe voltage increases. Initially, the voltage at terminal V1 must atleast exceed the sum of the forward voltage drops across diodes D1-D6.Thereafter, the shutoff voltage is determined by the characteristics oftransistor Q1, the forward voltage drop of diodes D1-D6, and theresistance of resistors R1 and R2 (having a net resistance of, forexample, 66.5 Ohms).

In this embodiment a full wave rectified voltage is applied betweenterminal V1 and ground, so that a unipolar, fluctuating sine wave isapplied in each half cycle. Accordingly, transistor Q1 conducts once thecombined forward voltage drop is reached and diodes D1-D6 begin toconduct, but stops conducting when the input voltage becomes too large.The conduction angle of transistor Q1 can be tailored to accommodate thenumber and the rating of diodes D1-D6. Thus, transistor Q is a powerrestricting device.

In this embodiment, the six diodes D1-D6 each have a forward voltagedrop of 24 V, that is, a total voltage drop of 144 V. Other embodimentsare anticipated. For example some embodiments may use four seriallyconnected diodes, each having a forward voltage drop of 36 V, that is, atotal voltage drop of 144 V. It will be appreciated that the totalvoltage drop can be modified for some embodiments, depending on whetherone desires a larger or smaller conduction angle, the ratings of thediodes, the available line voltage, etc. Good results are achieved whenthe forward voltage drop of each of the LEDs exceeds 8 V.

Referring to FIG. 2, a rectifier circuit is illustrated for providingthe power input for the light circuit of FIG. 1. In FIG. 2, a source ofalternating current VAC, which may be the ordinary power supplied by alocal utility, connects through fuse F1 across metal oxide varistorMOV1, which provides surge protection. Capacitor C1 is connected inparallel with varistor MOV1 to suppress RF transmission andinterference. A conventional full wave bridge 11 has its input connectedacross capacitor C1 to produce an output 12. It will be understood thathalf-wave bridges may be used or other type of rectificationarrangements may be used instead. Good results are achieved when thetime-varying voltage at output 12 has a peak voltage greater than 100 V.

Referring to FIG. 3, the previously illustrated transistor (transistorQ1 of FIG. 1) was replaced with current limiting resistors R3 and R4(which constitute another power restricting device). Specifically,diodes D7, D8, D9, D10, D11, and D12 are serially connected as before(cathode to anode) in that order. However, resistor R3 is seriallyconnected between diodes D8 and D9, and resistor R4 is seriallyconnected between diodes D10 and D11. This string is connected betweenpreviously mentioned terminal V1 and ground.

Referring to FIG. 4, a light strip is schematically illustrated as twoflexible substrates 14 and 16, mounted end two end. While two substratesare illustrated, it will be understood that some embodiments may employonly one substrate, or more than two substrates. In this embodimentsubstrates 14 and 16 are identical and each have four identical lightingcircuits M1, M2, M3, and M4. Each of these circuits M1-M4 is that shownin the FIG. 1. While the given number of lighting circuits M1-M4 isfour, in other embodiments a different number may be employed. TerminalV1 is that previously illustrated, while ground is identified asterminal GRD.

In this diagram substrates 14 and 16 are illustrated with their longer,lateral edges running right and left. Each of the light circuits M1-M4have a pair of solder pads connected to terminal V1 and a pair of solderpads connected to terminal GRD. Specifically, circuit M1 has solder padsP1 and P2 connected to its terminal V1, circuit M2 has solder pads P3and P4 connected to its terminal V1, circuit M3 has solder pads P5 andP6 connected to its terminal V1, and circuit M4 has solder pads P7 andP8 connected to its terminal V1. Also, circuit M1 has solder pads G1 andG2 connected to its terminal GRD, circuit M2 has solder pads G3 and G4connected to its terminal GRD, circuit M3 has solder pads G5 and G6connected to its terminal GRD, and circuit M4 has solder pads G7 and G8connected to its terminal GRD.

A pair of conductors 18 and 20 are shown positioned adjacent tosubstrates 14 and 16, on opposite sides of the substrates 14 and 16.Power is supplied to conductors 18 and 20 by rectifying circuit 22,which is as illustrated in FIG. 2. In particular, conductor 20 receivesthe high potential while conductor 18 is ground.

Each of the lighting circuits M1-M4 has a separated pair of leads(jumpers) acting as a connecting device to conductors 18 and 20.Specifically, lead J1 is soldered between pad P2 and conductor 20, whilelead J5 is soldered between pad G1 and conductor 18. Also, lead J2 issoldered between pad P4 and conductor 20, while lead J6 is solderedbetween pad G3 and conductor 18. Lead J3 is soldered between pad P6 andconductor 20, while lead J7 is soldered between pad G5 and conductor 18.Lead J4 is soldered between pad P8 and conductor 20, while lead J8 issoldered between pad G7 and conductor 18. It will be understood thatdifferent pads may be used as a matter of convenience. For example, leadJ1 could be connected between pad P1 and conductor 20.

It will be noted that substrates 14 and 16 are not directlyinterconnected and thus can be severed along line 24. In fact, none ofthe four light circuits M1-M4 on substrates 14 and 16 are directlyinterconnected and thus each substrate can be severed into quarters (onequarter, two quarters, or three quarters). In the case of severing,another rectifier circuit, similar to circuit 22, may be connected tothe left ends of the conductors 18 and 20 remaining in the severedsegment, and that segment will be able to operate without any negativeeffect caused by the severing.

Referring to FIGS. 5 and 6, a complementary pair of copper laminations24 and 26 are designed to be registered as shown and attached byappropriate adhesives to opposite sides of an intervening layer ofpolyamide, before being covered with a conventional solder mask (notshown). In the usual fashion, the copper laminations have been etchedwhile on the polyamide with the portions removed by etching illustratedherein in the color black. Laminations 24 and 26 are designed toimplement the circuit of FIG. 1, and the illustrated portion willrepeated on the remaining (unillustrated) portions to implement thesubstrate of FIG. 4 (substrate 14 or 16).

Lower lamination 26 is shown having previously mentioned solder pads P1,P2, G1, and G2 in the upper left corner, upper right corner, lower leftcorner, and lower right corner, respectively. Pads P1 and P2 areinterconnected by run B1, while pads G1 and G2 are interconnected by runB11. In this embodiment plated-through holes connect between upper andlower laminations 24 and 26, in order to separately connect lower padsP1, P2, G1, and G2 to upper pads P1′, P2′, G1′, and G2′, respectively.Pads P1 and P2′ are interconnected by run A1, while pads G1′ and G2′ areinterconnected by run A11.

Lamination 24 is shown segregated into isolated segments A1, A2, A3, A4,A5, A6, and A7. Segments A8 and A10 are interconnected by run A9.

Components previously mentioned in FIG. 1 are shown in phantom asfollows: (a) diode D1 connecting between segments A1 and A2, (b) diodeD2 connecting between segments A2 and A3, (c) diode D3 connectingbetween segments A3 and A4, (d) diode D4 connecting between segments A5and A6, (e) diode D5 connecting between segments A6 and A7, and (f)diode D6 connecting between segments A7 and A8.

Plated-through holes W1/W1′ connect together segments A4 and B4, whileplated-through holes W2/W2′ connect together segments B4 and A5. The neteffect of these plated through holes is to connect together segments A4and A5. It will be appreciated that the foregoing provides a serialconnection of diodes D1-D6 from pad P2 to run A9.

Run A9 leads to segment A10 and previously mentioned transistor Q1(shown in phantom) is mounted with its drain connected to segment A10.Run A11 has a spur A11′ that ends in a pad that connects to the gate oftransistor Q1. Isolated pad A12 connects on one end to the source oftransistor Q1, and on the opposite end to one terminal of each of theresistors R1 and R2 (also shown in phantom), whose other terminalsconnect to run A11. It will be appreciated that the foregoingarrangement produces the circuit previously described in FIG. 1.

It will be noticed that in lamination 26 segments B2, B3, B6, and B7 areisolated and are not designed to carry current. Instead, these segmentsare used as heat sinks to dissipate heat generated by components mountedatop upper lamination 24. In particular, segments B2, B3, B6, and B7thermally connect through plated-through holes H1/H1′, H2/H2′, H3/H3′,H4/H4′, respectively, to respective segments A2, A3, A6, and A7. Inaddition, segment B10 thermally connects through plated-through holesH6/H6′ to segment A10. Plated-through holes H1/H1′, H2/H2′, H3/H3′,H4/H4′, and H6/H6′ are referred to herein as a dedicated portion of theplated-through holes, designed to conduct heat without conductingcurrent.

It will be appreciated that the foregoing pattern repeats and that eachrepetition can operate independently. Each adjacent repetition can beseparated as desired by severing them apart at cutline 28/28′. Thesolder mask (not shown) covering laminations 24 and 26 can be marked toindicate the cutlines. As previously described, power is applied to theillustrated light circuit by applying a supply voltage between runs A1and A11 and for this purpose one of the pads P1, P2 is paired with oneof the pads G1, G2 to connect to conductors 18 and 20 and act as asupply source.

The ten plated-through holes 30/30′ (five pairs) connecting betweensegments A2 and B2 are designed to receive a non-functional componentsuch as dummy resistor (not shown). This nonfunctional component can besoldered into one of five positions, which signify a quality of thelighting strip. For example, the solder mask (not shown) at holes 30/30′can be marked to indicate a color temperature of the LEDs D1-D6 (e.g.,5000 K, 4000 K, 3000 K, 2700 K, or 2400 K).

Referring to FIG. 7, flexible enclosure 40 is an extrusion ofthermoplastic material, such as PVC, a high density polyethylene,polychlorotrifluoroethylene, an ionomer resin, or other plasticmaterial. Enclosure 40 has a periphery with an asymmetricalcross-section specifically, enclosure 40 has a pair of ridges 40A and40B on one side, and on the other side a single ridge 40C, which is at adifferent elevation than either of the ridges 40A and 40B. Theseasymmetrical ridges serve a purpose that will be described presently. Inthis embodiment enclosure 40 has an overall width of 1 inch (2.5 cm) andoverall thickness of ⅜ inch (1 cm), although other dimensions may beemployed depending on the available space, the materials used, the sizeand rating of the LEDs and other components, etc.

Enclosure 40 is tubular and has a longitudinal tunnel 38 containing alighting assembly, which includes printed circuit board 32 (board 32also referred to as a substrate) populated with the electricalcomponents previously described in connection with FIGS. 4-6. Diode D1is visible in this view. This assembly is identified as light strip 10.

Light strip 10 also has the leads J1-J8 illustrated in FIG. 4. Leads J1and J5 visible in this view and are shown soldered on the outside end toconductors 18 and 20, respectively, and on the inside end to respectivepositions 34 and 36 at substrate 32. Positions 34 and 36 correspond topreviously mentioned solder pads (pads G1 and P2 of FIG. 4). It will benoticed that enclosure 40 is extruded completely around conductors 18and 20, and is partially extruded around an outside portion of leads J1and J5. In this embodiment conductors 18 and 20 are each made ofstranded wire.

Longitudinal tunnel 38 is generally rectangular but has longitudinalslots 38A and 38B for holding the lateral edges of substrate 32, andlongitudinal gutter 38C that provides space for heat dissipation.

Referring to FIGS. 7 and 8, die 140 of FIG. 8 is designed to extrude thepreviously mentioned enclosure 40 of FIG. 7. Specifically, the inside ofdie 140 has flat upper and lower walls, a right sidewall having channels140A and 140B for forming previously described ridges 40A and 40B ofFIG. 7. The left inside wall of die 140 has a channel 140C for formingridge 40C of FIG. 7.

A die 138 is nested inside die 140 and is supported on top by posts142A, 142B, 142C, and 142D, and from below by lower posts 144A, 144B,144C, and 144D. The direction of extrusion is out of the drawing of FIG.8, and the posts 142A-142D and 144A-144D are set back enough thatextrudate will flow around them without leaving gaps. Previouslymentioned substrate 30 is shown traveling inside die 138 in the samedirection as the extrudate.

The previously mentioned tunnel 38 of FIG. 7 is formed by internal die138 which has approximately the same peripheral outline as the tunnel,including protrusion 138C for forming gutter 38C, and protrusions 138A138B for forming slots 38A and 38B. Die 138 deviates from the outline oftunnel 38 in the case of protrusions 138D and 138E on the right, andprotrusions 138F and 138G on the left. Protrusions 138D and 138G areformed by quarter-cylindrical walls that provide clearance for leads J5and J1, respectively, as well as for the other leads that follow behindthem. Protrusion 138E and 138F include semicylindrical walls thatprovide clearance for previously mentioned conductors 18 and 20,respectively.

In FIG. 7 conductors 18 and 20 as well as the adjacent portions of leadsJ1 and J5 are embedded inside the plastic material of enclosure 40. Toallow such an embedding, walls 138D-138G of FIG. 8 may have slits orapertures that allow extrudate to flow around conductors 18 and 20 andleads J1 and J5.

Also, after the first extrusion stage, the combined enclosure 40 andsubstrate 32 may be sent through a second die that compresses theenclosure, completes the flow of extrudate around conductors 18 and 20,and embeds the edges of substrate 32 inside notches 38A and 38B.

The overall length of the resulting light strip will depend on thenumber of substrates 32 that are installed. The individual substrateswill be preassembled end to end and pre-wired to conductors 18 and 20.If, for example, nine substrates 32 that are each 16 inches (40 cm) longare assembled end to end, the overall length will be 12 feet (or twicethat length with eighteen substrates 32). Since each substrate 32 hasfour banks (four of the circuits of FIG. 1), each substrate can bequartered as previously described in connection with FIG. 4. Two and aquarter substrates can be a abutted end to end to produce an overalllength of 3 feet (or double those amounts to produce an overall lengthof 6 feet).

Referring to FIG. 9, an alternate flexible enclosure 240 is extruded inthe absence of the substrate (substrate 32 of FIG. 8). Enclosure 240 hasthe same cross-section as enclosure 40 of FIG. 7 except for alongitudinal split 246. Accordingly, components corresponding to that ofFIG. 7 have the same reference numeral, except they are increased by200. Longitudinal split 246 splits the previously mentioned gutter(gutter 38C of FIG. 7) into two gutter halves, 238C and 238C′.

As before, enclosure 240 is extruded around conductors 18 and 20. Whileenclosure 240 is again partially excluded around leads J11 and J12 (andthe corresponding leads that follow), the leads are routed differentlyand emerge into gutter 238C/238C′. Since leads J11 and J12 follow a moretortuous path, they are longer. As will be explained presently,longitudinal split 246 is used as an opening for installing thepreviously mentioned substrate.

Referring to FIG. 10, previously mentioned enclosure 240 is shown lyingwith its longitudinal split 246 facing up. At one location split 246 isspread apart enough to insert the distal (forward) end of tubularspreading tool 248 between the split's opposing walls 246A and 246B.Previously mentioned substrate 32 is shown inserted through tool 248 tolie inside tunnel 238 as shown at the distal end of enclosure 240. Thedistal end of enclosure 240 can be squeezed lightly to hold the distalend of substrate 32 in place, as tool 248 is drawn backwardly. As tool248 is drawn backwardly (moving proximally), the spread-apart sectormoves, and this moving sector allows more and more of substrate 32 topass through the tool and fall into position inside enclosure 240.

In FIG. 10 previously mentioned diodes D5 and D6 are in one lightcircuit, and diode D1 is in the succeeding light circuit. (These diodesare shown in phantom in FIG. 10 because they are on the reverse side ofsubstrate 32.) As previously described, individual lighting circuits canoperate independently and can be severed apart. For this reason thesolder mask of substrate 32 has been marked at position 48 with astraight line overlaid with a scissors symbol to specifically indicatewhere to cut the substrate. It will be appreciated that the solder maskon the reverse side of substrate 32 can be also marked to indicate thecutline. These cutlines can be used when the assembler desires to make alight strip shorter than substrate 32.

In some cases the assembler will want a light strip that is longer thansubstrate 32, whose length in one embodiment was 16 inches (40 cm). Insuch a case, a new substrate will be inserted immediately following thefirst substrate. In practice a number of successive substrates can beinserted in this fashion to produce a light strip of various lengths.The last substrate that is inserted can be cut at one of the designatedcutlines to trim the light strip to the desired length.

As noted before in connection with FIG. 9, the embedded leads J11 andJ12 will emerge from the opposing faces of gutter halves 238C and 238C′.This feature is depicted in FIG. 10 with lead J14 emerging from gutterhalf 238C′ in wall 246A of split 246, and lead J15 emerging from gutterhalf 238C in wall 246B of split 246. It will be noticed that lead J14 isassociated with the light circuit to the left of cutline marking 48,while lead J15 is associated with the next light circuit to the right ofcutline 48. Such leads will emerge once on wall 246A and once on wall246B for every light circuit (i.e., once on each wall for every sixdiodes D1-D6, or once on each wall for every interval between cutlines).

The assembler will push substrate 32 past leads such as leads J14 andJ15, and will use a pick (not shown) to pull them outwardly so they areaccessible through split 246. Thereafter, when all these substrates 32destined for enclosure 240 are in place, the assembler may will use tool248 to open split 246 at every location where a connection must be madeto leads, such as leads J14 and J15. So for example, leads J14 and J15will be soldered to pads G2 and P1, respectively, which are shown inthis Figure on the opposite sides of cutline 48.

The assembly is completed by sealing split 246. This may be done bysending enclosure 240 through a die that compresses the enclosure andapplies heat to the split 246 to weld it closed.

Referring to FIG. 11, connector 350 has a cup-shaped shell 352 with arear wall 352A (shown in phantom) supporting a pair of pointed pins 354and 356. The inside of shell 352 is designed to fit around flexibleenclosure 40 of the light strip 10. In particular, groove 340C on theinside of shell 352 is designed to fit around ridge 40C. Grooves 340Aand 340B are shaped to fit around corresponding ridges on enclosure 40(ridges 40A and 40B of FIG. 7). Accordingly, connector 350 is keyed toenclosure 40 by means of grooves 340A, 340B, and 340C. Because thekeying is asymmetrical, connector 350 will only fit over one end ofenclosure 40 and will be unable to fit on the opposite end, even if theconnector is rotated 180°.

When shell 352 is pressed over enclosure 40 of light strip 10 pointedpins 354 and 356 are inserted into conductors 18 and 20 (FIG. 7),respectively. Since conductors 18 and 20 are each made of stranded wire,pointed pins 354 and 356 are able to insinuate themselves into thestrands and make electrical contact therewith.

Referring to FIG. 12, previously mentioned connector 350 is shown withits pointed pins 354 and 356 connecting through wall 352A to a pair ofwires 358 and 360 that are routed through cable 362 to housing 364.Housing 364 contains the circuit shown in FIG. 2 and that circuit'soutput 12 connects to wires 358 and 360 of FIG. 12. The power input VACof the circuit of FIG. 2 is represented in FIG. 12 as line 366terminating in utility plug 368 designed to receive line voltage from anordinary electrical outlet.

Referring to FIG. 13, housing 464 contains the circuit shown in FIG. 2,and that circuit's power input VAC is received through wire pair 466 ofline 468, which is hardwired to one of the power lines in a building.The output of the circuit in housing 464 is routed through a wire pairin cable 462 to the previously illustrated connector (connector 350 ofFIG. 12). The foregoing arrangement is intended for a more permanentinstallation or heavy-duty application. With this in mind, housing 464is attached to cover 470 of a utility box 472 that is attached tostructural component 474 (for example, a wall stud inside a wall). Suchan installation may be useful for certain high-power applications. Toaccommodate a high power environment, housing 464, in this embodiment,is an aluminum casting with cooling fins 464A.

Referring to FIG. 14, clip 576 is a U-shaped channel designed to holdlight strip 10 of FIG. 7. Clip 576 has a pair of opposing walls 576A and576B that are barbed on top to capture the light strip 10. Floor 576Chas ridges and grooves that provide an air passage under the light stripto allow heat dissipation. Clip 576 may be manufactured in a variety oflengths and can be cut to match the length of the specific light stripbeing installed.

To facilitate an understanding of the principles associated with theforegoing apparatus, its operation will be briefly described. Amanufactured length of light strip 10 of FIG. 7 (or the light stripassociated with the embodiment of FIG. 9) can be trimmed to a desiredlength by cutting through enclosure 40 at the position indicated bymarkings 48 (FIG. 10) or between abutting substrates 32. Severing inthis manner will not end affect the integrity of any of the lightcircuits shown in FIG. 1. As shown in FIG. 4 the light circuits arearranged in separate banks, each bank containing four light circuitsM1-M4. Because each of the light circuits M1-M4 are autonomous aninstaller can sever the light strip between any of the light circuits.Thus, an installer can cut between light circuits M1 and M2, betweenlight circuits M2 and M3, or between light circuits M3 and M4. Theinstaller can also cut a light strip between adjacent substrates, thatis, cutting along dividing line 24 of FIG. 4 to separate substrate 14from substrate 16.

In some cases, the overall length of the available light strip will beinsufficient. In such a case a splicing connector (not shown) can beused that has a shell 352 as shown in FIG. 11, but will be open onopposite sides of wall 352A. In this case, wall 352A will still have thepins 354 and 356 projecting from one side of the wall, but will have onthe opposite side another pair of pointed pins that align with pins 354and 356. Thus the conductors 18 and 20 in one light strip will bespliced together with the corresponding conductors 18 and 20 in theother light strip.

The end of the light strip that is not destined to receive such asplicing device or the connector of FIG. 11 will be capped by acup-shaped device (not shown). This capping device will havesubstantially the same shape as the distal portion of shell 352, willlack connector pins, and the outline of its mouth will be the mirrorimage of that shown in FIG. 11. Because this capping device, as well asconnector 350, make intimate contact with the periphery of enclosure 40,there is little chance of humidity or dust reaching the inside of theenclosure to adversely affect the operation of the light strip. Thequality of these seals can be enhanced by using an appropriate adhesiveor caulk.

Light strip 10 can be installed by first securing the clip of FIG. 14 inplace using adhesive, screws, nails, or other fastening devices.Connector 350 can be a pushed onto the end of light strip 10 as shown inFIG. 11, before or after snapping the light strip into clip 576. Powercan be supplied to connector 350 by using either the arrangement of FIG.12 or FIG. 13. A light switch (not shown) can be employed to turn lightstrip 10 on or off.

Conductors 18 and 20 supply power to each of the light circuits M1-M4(FIG. 4) that are contained in the trimmed light strip. It will benoticed from FIG. 4 that substrate 14 (as well as substrate 16) need notcarry current between individual light circuits M1-M4 and the greatestcurrent flowing on a substrate is that needed to power an individuallight circuit. Thus, while conductors 18 and 20 may be carryingrelatively high current to supply a large number of light circuits, theamount of current tapped off through each of the leads J1-J8 is onlythat needed to supply power to an individual one of the light circuitsM1-M4. Therefore, the current flowing on substrate 14 (or substrate 16and its successors) is relatively small and no heat is generated to anextent that the operation of LEDs D1-D6 or transistor Q1 (FIG. 1) willbe degraded.

As previously described in connection with FIG. 1, the current throughLEDs D1-D6 will be limited by transistor Q1. When the half wave linevoltage applied to terminal V1 reaches a voltage exceeding the sum ofthe forward conduction voltage drops of LEDs D1-D6, current will beginto flow. Current will begin to immediately flow at this stage sincedepletion mode, field effect transistor Q1 is arranged to immediatelyconduct when there is a small voltage at its drain D. As the voltage atterminal V1 continues to increase, eventually the voltage between gate Gand source S of transistor Q1 becomes large enough to shut off thetransistor thereby avoiding excessive current through LEDs D1-D6. Thevalues of resistors R1 and R2 are selected to control this shutoffpoint. The foregoing process reduces the conduction angle, reduces heat,and allows tighter current control. In addition, the foregoing circuitcan operate with a dimmer of the type that functions by reducing theconduction angle or by scaling down the amplitude of the AC voltage.

It is appreciated that various modifications may be implemented withrespect to the above described embodiments. The illustrated light stripscan be modified to have a different number of LEDs, which can bearranged in multiple rows or staggered in some other fashion. Also thevarious dimensions can be altered depending upon the desired lightoutput, temperature stability, space available, etc. Instead of theabove described extrusion, some embodiments may enclose a substrate bypotting materials such as silicone, or the assembly may be made byovermolding, or by other processes.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

The invention claimed is:
 1. A light strip comprising: a pair ofconductors; a flexible enclosure extruded around said pair ofconductors; and a lighting assembly including one or more flexiblesubstrates positioned within said enclosure and populated with aplurality of light circuits, said one or more substrates being spacedfrom said pair of conductors, said lighting assembly having a pluralityof connecting devices for electrically coupling said lighting assemblyto said pair of conductors, said one or more substrates including aplurality of substrates mounted end to end in said flexible enclosure,said plurality of substrates each connecting separately to said pair ofconductors, said plurality of connecting devices each comprising aplurality of separated pairs of leads, each separated pair beingelectrically connected between said pair of conductors and acorresponding one of said plurality of light circuits, the separatedpairs of leads including a plurality of first leads and a plurality ofsecond leads, said plurality of first leads being directly connected toa plurality of spaced points on a first one of said pair of conductors,said plurality of second leads being directly connected to a pluralityof spaced points on a second one of said pair of conductors.
 2. A lightstrip according to claim 1 wherein each of said plurality of lightcircuits include a power restricting device.
 3. A light strip accordingto claim 1 wherein said flexible enclosure is partially extruded aroundsaid separated pairs of leads.
 4. A light strip according to claim 3wherein said flexible enclosure is extruded with a longitudinal splitthat is open to allow installation of said one or more substrates.
 5. Alight strip according to claim 1 wherein said one or more of saidsubstrates each has a given number of said plurality of light circuits,each of said given number of light circuits having a pair of solder padsseparately connected to said pair of conductors.
 6. A light stripaccording to claim 5 wherein said given number of light circuits (a) arearranged end to end, and (b) are adapted to be severed between anyadjacent pair of said given number to operate autonomously.
 7. A lightstrip according to claim 1 comprising: a rectifier circuit locatedoutside said flexible enclosure for applying to said lighting assembly apulsating voltage having a peak voltage in excess of 100 volts.
 8. Alight strip according to claim 7 wherein said rectifier circuitcomprises: a housing; a utility plug; a line connected between saidhousing and said utility plug; and a cable connecting between saidhousing and said pair of conductors.
 9. A light strip according to claim7 wherein said rectifier circuit comprises: a housing with cooling fins;and a cable connecting between said housing and said pair of conductors.10. A light strip according to claim 7 wherein said pair of conductorseach comprise stranded wire, said rectifier circuit comprising: aconnector having a shell and a pair of pointed pins within said shell,said shell being sized to fit over an end of said flexible enclosure,said pair of pins being adapted to be inserted into said pair ofconductors.
 11. A light strip according to claim 7 wherein said flexibleenclosure has a periphery with an asymmetrical cross-section, saidrectifier circuit comprising: a connector having a shell and a pair ofpins within said shell, said shell being keyed to fit over only one endof said flexible enclosure.
 12. A light strip according to claim 1wherein said plurality of light circuits each comprise: a depletion modefield effect transistor; a serially connected plurality of lightemitting diodes coupled to said transistor; and a power input coupled tosaid transistor and said plurality of light emitting diodes, said powerinput adapted to receive a time varying voltage varying overpredetermined cycles, said transistor arranged to conduct over a limitedconduction angle that ensures conduction at the start of a half cycle.13. A light strip according to claim 12 comprising: a resistive element;a pair of power input terminals adapted to connect to a power source andsupply current to resistive element, said transistor, and said seriallyconnected plurality of light emitting diodes, said transistor beingserially connected between said resistive element and said seriallyconnected plurality of light emitting diodes, said transistor having agate connected to one of said pair of power input terminals.
 14. A lightstrip according to claim 1 wherein said plurality of light circuits eachcomprise: a plurality of light emitting diodes each having a forwardvoltage drop exceeding 8 volts.
 15. A light strip according to claim 1wherein each of said one or more substrates comprises: an insulatinglayer sandwiched between a pair of copper laminations that are etchedinto separate sections, said pair of copper laminations having aplurality of plated-through holes, a dedicated portion of which arearranged to conduct heat without conducting electrical current.
 16. Alight strip according to claim 15 wherein a marked portion of saidplurality of plated-through holes are arranged to receive anon-functional component that signifies a quality of a corresponding oneof said one or more substrates.
 17. A method for making a light striphaving a pair of conductors and one or more flexible substratespopulated with a plurality of light circuits, the method comprising thestep of: extruding a plastic material around said pair of conductors toform a flexible enclosure sized to encompass said one or more flexiblesubstrates and maintain a spacing between said pair of conductors andsaid one or more flexible substrates, wherein the step of extruding theplastic material is performed to leave a longitudinal split, the methodincluding the step of: installing the one or more substrates through thelongitudinal split; connecting said pair of conductors to said pluralityof light circuits; and sealing the split.
 18. A method according toclaim 17 employing a spreading tool, the step of installing the one ormore substrates including the steps of: initially spreading a portion ofthe longitudinal split with said spreading tool while a distal end ofone of said one or more substrates is inserted past said tool andthrough said longitudinal split; and proximally moving said spreadingtool to spread a moving sector of the longitudinal split to allowprogressive insertion of said one or more substrates.
 19. A methodaccording to claim 17 employing a plurality of separated pairs of leads,the method including the step of: electrically connecting each separatedpair to said pair of conductors before extruding the plastic material,the step of extruding the plastic material being performed to partiallyencompass an inner portion of each separated pair of leads.